Ethanol can be acquired from biomass such as a sugar cane and a corn as so-called biofuel. Such carbon neutral ethanol can reduce carbon dioxide (CO2) by being replaced with petroleum fuel. However, the market price of ethanol is higher than that of petroleum fuel and it hinders the popularization of ethanol as fuel.
A manufacturing process of ethanol originated from biomass is roughly classified into a saccharification process, a fermentation process and a dehydration process. Predetermined energy is required to execute each process. However, out of these processes, the dehydration process requires approximately 25% of the whole energy required for the manufacturing process. Accordingly, if an aqueous ethanol solution can be utilized for fuel as it is without using the dehydration process, an amount of energy required for a manufacturing process of alcohol can be reduced and a price of ethanol can be kept down.
In the meantime, efficiency of an engine utilized for a power source in various fields can be effectively enhanced by recovering its exhaust heat. Above all, it is conceivable that an exhaust heat recovery system utilizing the reforming of fuel is important to enhance the efficiency of the engine because the number of parts is small and this exhaust heat recovery system can be operated at a lower cost, compared with another exhaust heat recovery system.
Patent Literature 1 discloses an ethanol engine system in which an aqueous ethanol solution reserved in a reservoir tank is directly injected into a combustion chamber of an engine, a reformed gas generated in a reformer using the aqueous ethanol solution for material is supplied to the engine and motive power is generated by combusting ethanol included in the aqueous ethanol solution and the reformed gas in the combustion chamber.
The aqueous ethanol solution is fuel suitable for the exhaust heat recovery system because the reformed gas including hydrogen can be generated from the aqueous ethanol solution by an endothermic reaction by utilizing its exhaust heat.
Further, as hydrous ethanol has a great latent heat of evaporation to its calorific value, the inside of the combustion chamber can be cooled by directly supplying the hydrous ethanol to the engine. Thereby, a quantity of heat that escapes in a cooling water for the engine can be reduced and the efficiency of the system can be enhanced by increasing energy by exhaust heat for shaft power.